MG Car Repair: brake bleeding, power bleeder, mightyvac

Question
Howard, follow up on previous question.  1970 MG Midget.  I have done everything you have told me to do so far.  However, when trying to force calipers out when pads removed revealed that the caliper will not move.  When pumping the brakes, the fluid goes down and when I stop, it comes back up again (in the fluid reservoir.  Also, I have tried to bleed the brakes with a mightyvac and noticed the I cannot hold pressure in tool when the bleeder is closed.  I pressurize the system with a power bleeder and it holds 10 psi overnight.  What next?  

Answer
Andy, If you remove the pads and step on the brakes and the pistons don't come out of there bore any, then the calipers are bad (frozen) and need to be either rebuilt or replaced. It is no use fooling with it until that is fixed. The fluid returning could be the rear brakes completely out of adjustment and that needs correcting too.
Howard